The beginning of any good network begins with planning and one of the major planning points involved is the network topology. Network topologies are made up of both physical and logical maps, each variant having positive and negative aspects, as well as applications where one type would be more appropriate. Many modern network layouts are hybrids of physical and logical networks. One of the most basic types of topologies is Point to Point, where a connection is established between two nodes only to communicate between the two. One of the most basic examples of this is two cans on a string; they are connected to each other just so the two can communicate. This relationship can also be observed with two computers connected via a crossed Ethernet cable. This connection method is also used for communication via telephone, but this is achieved in a logical way. Switched telecommunications systems are used to create a link between two telephones to connect them and allow communication between the two and then cut them off when the connection is no longer needed. Point to point communication in modern times is still prevalent, but is achieved using more complex networks with the help of network logic and can be used to describe many of the connections between individual parts of a network. The next network topology is the Bus topology. Bus topologies are normally made up of a backbone or a means of transport to which all the nodes are connected. The linear bus configuration has only two endpoints, and any information transmitted across the network is received by all nodes at the same time. Although networks based on a bus topology are relatively cheap to set up, they do not scale well. When you try to add more... half the paper... you put the whole network down." (Learn Networking) Another large scale network topology would be the Mesh topology. Mesh topologies are full mesh or mesh partial. The full-mesh has every node in the network connected to every node in the network. This configuration ensures constant capacity to transfer data and is truly redundant, but it would be very expensive to implement. The partial mesh only connects all the other nodes in the network while still allowing redundancy at a reduced cost and this configuration is commonly used in backbone networks to ensure that they constantly have the capacity to transfer data. With all the possible topologies there are so many different types of configurations possible. The features of modern topologies ensure that the global data transfer to telephone calls is possible through physical and logical means at every level.